Ellipsograph



1957 A. E.1NEIGLICK 2,777,199

ELLIPSOGRAPH Filed June 50, 1955 m a. INVENTOR.

ATT'YS r 2,777,199 ICE Patented Jan. 15, 1957 ELLIPSOGRAPH Anders Emil N eiglick, Winnetka, Ill.

Application June 30, 1953, Serial No. 365,139

1 Claim. (Cl. 33-18) This invention relates to structural improvements in ellipsograph instruments, the mechanical principles of which are well known in the art.

The main objects of this invention are to provide an improved construction for such instruments to render them more efiieient in operation especially with respect to the convenience of holding them in place on a flat surface and locating them with respect to the major and minor axis lines of an ellipse that is to be drawn; and to provide a structure which is more accurately controlled and less likely to be aifected by wear that would produce inaccurate movement of the scribing point.

A specific embodiment of this invention is illustrated in the accompanying drawings, in which:

Figure 1 is a perspective top view of an ellipsograph constructed according to this invention.

Fig. 2 is a sectional detail of the scribing unit taken on a Vertical plane through the line 22 of Fig. 1.

Fig. 3 is a top view of the same.

Fig. 4 is a similar sectional detail of the beam mounting elements of the pivotal connectionthat moves along the major axis of the ellipse that is to be drawn, the section being taken on intersecting vertical planes represented by the line 44 of Fig. 1.

Fig. 5 is a section taken on the line 5-5of-Fig. 1. "Fig; 7 is a side elevation of the traveler unit of the minor guideway.

Fig. 6 is a section of the base plate taken on the line 6-6 of Fig. 1.

In the form shown in the drawings, the base of the instrument is a flat plate 10 of transparent plastic material, preferably of triangular form and having a straight edge 11 for registry with a line 12 on the drawing representing the major axis of an ellipse which is to be drawn.

The guiding edge 11 is beveled, as indicated in Fig. 3, so that its registration with the line 12 can be clearly viewed from above and so that the plate 10 will not obstruct movement of the marking tip 13 of the scribing unit to move approximately up to such line 12. The plate 10 has friction pads 14 embedded in its lower surface, as indicated in Fig. 6, to prevent the instrument from accidently skidding on the surface of the drawing against which it is held by downward pressure of the operators fingers.

The general principle upon which ellipsographs operate is that of having a scribing instrument carried by a beam which has two pivotal axes, one indicated in the drawing by the pivot 15 mounted for travel along the major axis of the ellipse, and the other indicated by the pivot 16 mounted for travel along the minor axis of the ellipse.

The pivots 15 and 16 during a scribing operation are fixed with respect to the beam so that a swinging movement of the beam causes pivot 15 to travel along the major axis and pivot 16 to travel along the minor axis, so as to carry the marking tip of the scribing instrument in an elliptical path. The size of the ellipse is determined by the position of the scribing point 13 with respect to the pivots 15 and 16. The distance of the scribing tip 13 from the pivot 16 that travels along the minor axis equals one-half the length of the major axis, and the distance of the marking tip from the pivot 15 that travels along the major axis equals one-half the length of the minor axis of the ellipse.

In theory, the marking tip and the two pivotal axes are in accurate straight line alinernent with each other at the plane of the drawing. In the instrumental embodiment, these three points may dififer in elevation but should lie in a common vertical plane normal to the bottom surface'of the plate 10. r

In the construction shown, the plate 10 has fixed on its upper surface a rail 17 that is spaced inward from and parallelwith the edge 11 and serves as a guideway which, for convenience of reference, will be called the major guideway since it guides the movement of the pivot 15 along the major axis of the ellipse.

correspondingly, a rail 18 attached to the plate 10 and extending along the upper surface of the plate at right angles to the rail 17, at the midpoint of the length of the latter, serves as a guideway for the movement of the pivot 16 along the minor axis of the ellipse. In the form shown, the rails 17 and 18 are Lshaped in cross section andcarry a major traveler member 19 and a minor traveler member 20, respectively, these being formed to snugly embrace the upper or head portion of their rails so as to slide along the rails freely without tilting movement of any kind".

In my improved construction, the scribing beam 21 is a straight bar of uniform cross'section and has laterally extending arms or bracket members 22, 23 and 24' to carry the scribingunit and pivots a sufficient distance to one side of the beam 21 so that at no position of the beam 21 does it obstruct the operators clear vision from above of the registration of the edge 11 with the major axis line 12 of the ellipse that isto be drawn.

The" displacement of the beam 21 to one side of the plane definedby the axes of the pivotslS and 16 and the marking tip 13 is equal at all points so that adjustment of the bracket members 22 and 23 along the beam will not disturb this relationship.

In the form shown, the bracket 24 is permanently fixed on the beam 21 and the brackets 22 and 23 are adjustable along the beam but are secured at their adjusted locations on the beam 21 by friction clamps operated by knurled thumb screws 25 and 26, respectively, and the bar has a handle 27 by means of which it is swung about the axes 15 and 16.

The guideway bar 13 terminates short of the guideway bar 17 so that the traveler member 19 can travel from end to end of the bar 17 to enable a complete semiellipse to be drawn at one setting of the device.

As will be seen from Fig. 7, the traveler member 20 has an overhanging arm 20.1 of suflicient length to allow the pivot 16 to come into vertical alinement with the edge 11 of the plate 10 when the traveler member 20 abuts against the rail 17.

As will be seen from Fig. 4, the bracket arm 23 consists of two parts shaped to embrace the beam 21 and to be pressed together to grip the beam 21 to lock the bracket 23 by means of the thumb nut 26. The pivot structure 15 is such as to provide freedom of pivotal movement that is not disturbed by the setting or release of the clamping engagement of the bracket 23 with the beam 21.

The structure of the scribing unit is shown in Fig. 2 in detail and comprises the bracket arm 22, which functions as the principal part of a pencil carrier member, that is tightened or loosened in its engagement with the beam 21 by a clamp plate 22.1 tiltable on a lug 22.2. The arm 22 and plate 22.1 are shaped so as to embrace the beam 21 and prevent any tilting or sliding movement of the pencil point relative to the beam 21 when clamped together by the screw 30 and knurled nut 31.

The bracket 22 or carrier member, has an upstanding forward or back by rotation of the butt end of the pencil housing. The holding member 33 is held in its sliding relation to the post 32 by a u-shaped strap 39 that slidably embraces the post 32 and has its arms attached to the sides of the member 33. The strap 39, besides guiding the movement of the member 33 along the post 32, also serves as a limit stop to the downward movement of said member 33 by abutting against the arm 22 to which position it is normally, urged by the spring 34 to assure that the scribing tip or pencil point 13 will be held in contact with the drawing board with slight pressure.

In operation, the plate 10 is laid on the drawing board with its edge 11 defining the position of the major axis of the ellipse that is to be drawn and with center index 111 on said edge 11 at the center point of the ellipse. The distance between the pencil point 13 and pivot 16 having been set to equal one-half of the length of the major axis of the ellipse and the pivot 15 having been set at a distance from the pencil point equal to one-half of the minor axis of the ellipse, one-half of the ellipse is drawn by swinging the beam through an angle 180 with one setting of the plate 10 and the other half is similarly drawn with the plate 10 turned to the opposite side of the major axis line. The plate 10 enables the device to be held firmly in place by pressure of the operator's fingers of one hand while the beam is swung by his other hand. If in laying out the major axis a point is indicated thereon inward from either end thereof a distance equal,

to the half length of the minor axis, the spacing of the pivot 15 and the pencil point 13 with respect to the pivot 16 about which the scribing beam 21 is swung can be readily adjusted while the device is held in contact with the drawing board without any other measurements. To this end, the fact that the knobs 25, 26 and 27 are all upstanding enables such adjustment to be made with one hand manipulating the knobs 25 and 26 while the beam is parallel with the edge 11 and the plate is held firmly against the drawing board with the other hand.

Although but one specific embodiment of this invention is herein shown and described, it will be understood that numerous details of the structure shown may be altered or omitted without departing from the spirit of the invention as defined by the following claim.

I claim:

In an ellipsograph, a scribing beam, a scribing unit carried thereby comprising an arm extending across and having clamp means embracing said beam for sliding and locking engagement therewith, a bar extending upward from said arm and having a top portion bent to one side of said beam, a pencil-carrying block having a cylindrical extension on top thereof extending through a bore in said top portion of said bar, said block having a passage therethrough slidably fitting the vertical portion of said bar for limited vertical movement thereon, said block and its cylindrical extension having a bore therethrough to hold the pencil, and a compression spring bearing between said block and said top portion to normally urge said block downward.

ReferencesCited in the file of this patent UNITED STATES PATENTS 336,834 Boyle Feb. 23, 1886 1,327,154 Golden Jan. 6, 1920 1,422,345 Douglas July 11, 1922 2,646,623 Coats July 28, 1953 FOREIGN PATENTS 395,458 Germany May 13, 1924 250,016 Italy Sept. 2, 1926 112,764 Austria Apr. 10, 1929 590,749 Great Britain July 28, 1947 

